@WTFis2020, I really, really feel for you. I was you a year ago after 26 years, no kids sadly, and aged 59, with no job. Mine was exactly as described in Runaway Husbands. I found emails indicating that he had gone back to his teenage girlfriend who he last dumped 28 years ago, having already dumped her once before. He denies the affair even when presented with the emails! Totally irrational.
My life is infinitely better now. I’m taking on the house, have got several new, well-paid roles, and decree nisi date. This comes after many months of really hard times, the hardest of my life so far. You need support around you, medical help if things get worse, and therapy/counselling saved my life, literally. And some wonderful online friends via mumsnet.
Best advice I can give has been given already. Look after yourself and the DC. He does not care and will not care. He may ultimately want to be friends. Be alert to the fact that he will want the best financial settlement he can get for himself and anyone else on the scene. The ex painted me to be a horrible person, to justify his actions, and lied not only to me but also to his family and mutual friends. This is a very special kind of marriage breakdown and is traumatic. Everything you feel and describe is completely normal. This is about him and his lack of character, not about you.
Our thread is ‘Some Friendly Words’. It will be back a few pages now as we Warrior Women felt that time had come to let it lapse naturally. Reading back over it may help you to feel less at a loss and alone and there are useful resources there for support.
Good luck, Warrior-Up, and know that you will thrive once you are out of the chaos of the next time.